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The primary advantages of Fischer esterification compared to other esterification processes are based on its relative simplicity. Straightforward acidic conditions can be used if acid-sensitive functional groups are not an issue; sulfuric acid can be used; weaker acids can be used with a tradeoff of longer reaction times.
The Fischer indole synthesis. This reaction can be catalyzed by Brønsted acids such as HCl, H 2 SO 4, polyphosphoric acid and p-toluenesulfonic acid or Lewis acids such as boron trifluoride, zinc chloride, and aluminium chloride. Several reviews have been published. [3] [4] [5]
In acid-catalyzed Fischer esterification, the proton binds to oxygens and functions as a Lewis acid to activate the ester carbonyl (top row) as an electrophile, and converts the hydroxyl into the good leaving group water (bottom left). Both lower the kinetic barrier and speed up the attainment of chemical equilibrium.
The acid-catalyzed hydrolysis of an ester and Fischer esterification correspond to two directions of an equilibrium process. Basic hydrolysis of esters, known as saponification, is not an equilibrium process; a full equivalent of base is consumed in the reaction, which produces one equivalent of alcohol and one equivalent of a carboxylate salt.
Fischer glycosidation (or Fischer glycosylation) refers to the formation of a glycoside by the reaction of an aldose or ketose with an alcohol in the presence of an acid catalyst. The reaction is named after the German chemist, Emil Fischer , winner of the Nobel Prize in chemistry, 1902, who developed this method between 1893 and 1895.
Illustrative is the base-catalyzed hydrolysis of esters, where the produced carboxylic acid immediately reacts with the base catalyst and thus the reaction equilibrium is shifted towards hydrolysis.) The catalyst stabilizes the transition state more than it stabilizes the starting material.
The Fischer–Tropsch process (FT) is a collection of chemical reactions that converts a mixture of carbon monoxide and hydrogen, known as syngas, into liquid hydrocarbons. These reactions occur in the presence of metal catalysts , typically at temperatures of 150–300 °C (302–572 °F) and pressures of one to several tens of atmospheres.
The mechanism of acid-catalyzed hydrolysis of esters is the reverse of Fischer esterification. Acid is only required in catalytic amounts, as in Fischer esterification, and an excess of water drives the equilibrium towards carboxylic acid and alcohol.